Granular bleaching agent composition and method for making thereof



United States Patent Oflice 3,522,184. Patented July 28, 1970 v 3,522,184 GRANULAR BLEACHING AGENT COMPOSITION AND METHOD FOR MAKING THEREOF Yunosuke Nakagawa, Chiba, and Iwao Maruta, Ichikawashi, Japan, assignors to Kao Soap Co., Ltd., Tokyo, Japan, a corporation of Japan No Drawing. Filed Apr. 27, 1967, Ser. No. 634,124 Claims priority, application Japan, May 2, 1966, 41/27,820 Int. Cl. Clld 7/18, 7/56 U 5. Cl. 252-99 3 Claims ABSTRACT OF THE DISCLOSURE A method of making a granular bleaching agent composition, and the resulting product, in which a solid powdery bleaching agent mixture containing sodium perborate and at least one granulating assistant selected from the group consisting of magnesium sulfate, beryllium sulfate, potassium chloride, potassium nitrate, sugar and sodium borate is moved while it is heated in order to granulate said mixture.

FIELD OF THE INVENTION This invention relates to bleaching agent compositions and, more particularly, relates to granular bleaching agent compositions containing sodium perborate as a bleaching component and obtained by an improved granulating method.

Thepresent invention provides a bleaching agent composition having the desirable characteristics that it is convenient to handle, is high in solubility, will not agglomerate but will be free flowing while it is stored, does not fly and disperse as a fine powder and therefore will not irritate the mucous membranes of the eye and nose when it is used.

DESCRIPTION OF THE PRIOR ART It is conventional in bleaching clothes or the like to prepare a bleaching bath solution by adding a pH adjusting agentor a surface active agent to promote the permeation of the bath solution into the material to be bleached instead of preparing a solution of only a bleaching ingredient. However, when the amount used is very small or a little larger, as in a home or shop, it will be very inconvenient to individually acquire the required ingredients. Therefore, it is usual that the agent is so mixed and prepared in advance as to be of composition adapted to the use.

Such composition is generally available as a fine powder or in a granularity close to that of a powder or a type of product made by merely mixing such fine granular raw material ingredients is marketed. However, such powdery agent is apt to fly and disperse, irritates the mucous membranes of the eye and nose and is inconvenient to use. As a measure for overcoming such defects, it is known to once make such a composition into a slurry by adding a large amount of water and then to make a coarse granular dried product by drying the slurry With a dryer. However, in such method, the effective oxygen in the product will be reduced so much in the drying step that it is difiicult .to obtain an excellent product. In order to improve it, there has been suggested a method wherein a composition to which is added a stabilizer is sprayed and dried. For example, in German Pat. No. 1,071,874, a composition to which is added cellulose glycolate, sodium silicate or magnesium silicate is sprayed and dried. Further, in British Pat. No. 818,374, a composition containing sodium perborate and sodium tripolyphosphate in an amount larger than half the content of sodium perborate is sprayed and dried. Even by these methods, it is very difficult to perfectly prevent the decomposition. In U.S. Pat. No. 2,876,200, there is disclosed a method wherein ingredients other than sodium perborate are mixed in advance, the mixture is made into a fiuid slurry by adding water, the slurry is sprayed and dried by an ordinary method, sodium perborate is mixed with said sprayed and dried material and .the mixture is treated at high temperature so that the molten sodium perborate maybe fused to the sprayed and dried material. However, in this method, there is required a step of making a basic material by spraying and drying in advance and the production is very troublesome.

SUMMARY OF THE INVENTION In the present invention, it has been discovered that, when a proper motion is given to a raw material mixture conditioned to always contain one or more of such specific substances as are mentioned in detail later and containing all of the raw material ingredients by stirring or the like while heating it at a proper temperature, a desirable granular composition will be obtained. The thus obtained granular composition has the desirable properties that, when it is cooled to room temperature, it will be in a dry state, the composition is homogeneous, it is high in solubility, it will not agglomerate while it is stored and it will scarcely fly and disperse.

In the present invention, the above-mentioned heating temperature may be generally 64 to 95 C. There are various methods of giving a motion to the raw material mixture. For example, there is a method wherein the raw material ingredients are contained in a rotary container and the container is properly rotated. For this purpose, a rotary kiln or a V-shaped or conical blender can be used. Needless to say, the present invention is not limited to this method. The heating time may be generally about 5 to 30 minutes. A longer heating time is unnecessary. Further, in the present invention, some factors for regulating the granularity are considered. Principal factors are the raw material composition and the given speed of motion. If the given speed of motion is too large, no coarse grains will be formed. If the speed of motion is too small, a very long time will be required for the coarse granulation.

The specific substances to be used in the present invention are selected from the group consisting of:

The composition should always contain one or more of these substances (which shall be called a granulating assistant hereinafter) together with sodium perborate. It

is proper that 10 to percent sodium perborate and l to 20 percent of the above-mentioned granulating assistant should be contained in the total raw material mixture composition.

A perborate has been often added in addition to a surface active agent to a washing agent composition for domestic uses. In such case, magnesium sulfate may be added and used. But such magnesium salt is added and used only to further promote the bleaching effect or to prevent the decomposition of the sodium perborate. The purpose for and the amount of such use are quite different from those of the present invention. For example, in British Pat. No. 944,121, 300 to 420 p.p.m. of magnesium are added in the form of MgSO -7H O as a stabilizer in a process of producing sodium perborate of a bulk specific gravity of less than 0.7 to be used for a washing agent composition. Further, for example, in US. Pat. No. 2,838,459, a magnesium ion (Mg++) dissociat ing substance is added as a stabilizer to a hot alkali solution of hydrogen peroxide or sodium peroxide to be used for bleaching fibers.

In the composition of the present invention, there can be further mixed substances which are desirable in preparing a bleaching bath such as, for example, a chelating agent such as ethylene diamine tetracetate, an aluminum container corrosion inhibitor such as sodium silicate and a pH adjusting agent such as an alkali carbonate salt.

A fluorescent dye or a surface active agent or the like may be mixed in the granulating assistant so that it can be used also for fluorescent dyeing or washing. Further, in order to increase the volume or washing force, an inorganic salt, such as sodium sulfate or sodium tripolyphosphate, or an organic compound, such as carboxymethyl cellulose, may be mixed in the granulating assistant.

There have been already adopted various method of binding powders in granulating them, such as, for example, by means of a binding medium such as water or a pastes solution or by crystallization or a chemical reaction. However, the granulating mechanism in the present invention is that sodium perborate is softened by heating so as to bind the composition powder and, therefore, it is not necessary to use any additional binder for binding the powder. Further, as the present invention is not a known conventional so-called melting granulation, it is not necessary at all that all the composition should be in or near a molten state. It is rather necessary that the components in the composition other than the perborate should be in a solid state throughout the entire granulating process.

Though the operating mechanism of the above-mentioned granulating assistants in the present invention, such as magnesium sulfate and potassium chloride, is not clear, it is a fact as is made clear in the below-mentioned examples that, if such essential component is not present, the powder will not be granulated or will be very imperfectly granulated.

As it is not necessary to add water or a binder containing water for binding purposes, it is not necessary to dry the grains after the granulation. If the powder is properly granulated, the granularity will be so uniform that it will not be necessary to recrush the grains. Therefore, grains of a desirable strength can be obtained by merely cooling them to room temperature after the granulating treatment.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention shall now be explained with reference to the following examples:

Anhydrous sodium sulfate Magnesium sulfate (T-hydrate) 1 The parts are by weight here and also in the following examples.

First of all, mixtures of compositions A and B in Table 1 were prepared. Both mixtures passed through a sieve of 60 mesh size. (This is also the case in the following examples.) When a container Was filled with such mixtures, a considerable amount of the powder was seen to fly and disperse. When each mixture was left at 30 C. under a relative humidity of 80 percent it agglomerated in 7 days.

On the other hand, a container made of glass was filled to its capacity with each mixture, was rotated quietly at 80 C. for 2 minutes and was then left at room temperature.

The composition A became granulated and its granularity distribution was as listed in the following table:

Granularity: Yield in percent On a sieve of 24 mesh 38 24 to 32 mesh 45 32 to 60 mesh 13 Below a sieve of 60 mesh 4 On the other hand, the composition B in which no magnesium sulfate had been mixed did not granulate as did the composition A and it all passed through a sieve of 60 mesh, the same as the initial raw material mixture. Further, when the composition A as granulated was left at 30 C. under a relative humidity of percent for 7 days, no agglomerating phenomenon occurred.

The oxidation ability of the composition A after the granulation was substantially exactly the same as before the granulation.

EXAMPLE 2 A mixture of the composition stated in Table 2 was prepared.

Three kg. of this mixture were placed in a V-shaped blender of a capacity of 5 liters and the blender was rotated at 15 rpm. at 70 C. The mixture was taken out in 15 minutes and was left to cool to room temperature. Its granularity distribution was as follows:

Percent Remaining on a sieve of 32 mesh size 74 32 to 60 mesh size 23 Below a sieve of 60 mesh size 3 EXAMPLE 3 There was prepared a mixture of 25 parts of sodium perborate NaBO -4H O, 30 parts of sodium pyrophosphate, 38.5 parts of sodium sulfate, 10 parts of sodium higher alkyl sulfate, 33.5 parts of sodium sulfate, 1 part of carboxymethyl cellulose, 0.5 part of Whitex BO Conc and 10 parts of potassium chloride. All the mixture passed through a sieve of 60 mesh size. When it was heated at C. for 5 minutes and was granulated, substantially all of it became coarse grains which remained on a sieve of 32 mesh size.

EXAMPLE 4 A mixture of the composition listed in Table 3 was prepared.

TABLE 3 Parts Sodium perborate NaBO -4H O 35 20 Sodium bicarbonate Sodium sulfate 32.8 Sodium alkyl benzene sulfonate (powder product containing 40% sodium sulfate) Whitex BO Conc 0.2 Beryllium sulfate BeSO -4H O 5 Twenty kg. of this mixture were placed in a cylindrical rotary blender of a capacity of liters and were rotated at 30 r.p.m. at 68 C. The mixture was taken out in 20 minutes and was left to cool at room temperature. Its granularity distribution was as follows:

Example 5 When a mixture as listed in Table 4 was granulated as in Example 1, it became favorably granular. There was substantially no reduction of the concentration of effective oxygen before and after the granulation.

TABLE 4 Parts Sodium perborate 30 Sodium tripolyphosphate Sodium sulfate 38.8 Sodium silicate 3 Sodium higher alkyl sulfate 3 White); BO Conc 0.2 Magnesium sulfate 5 EXAMPLE 6 A mixture as listed in Table 5 was prepared.

TABLE 5 Parts Sodium perborate NaBO -4H O 50 Sodium phosphate 20 Sodium sulfate Beryllium sulfate BeSO -4H O 5 In the same fashion as in Example 4, the mixture was rotated at r.p.m. at 69 C., was heated for 20 minutes, was granulated and was then left to cool at room temperature. There was produced a uniform fine powdery granular product of substantially more than 24 mesh size having no flying and dispersing property.

EXAMPLE 7 A mixture of a composition as listed in Table 6 was prepared.

TABLE '6 Parts Sodium perborate 40 Sodium tripolyphosphate 50 Potassium chloride 10 The mixture was granulated in the same way as in Example 2. The concentration of effective oxygen after the granulation did not substantially reduce. The granularity distribution was as follows:

Percent Remaining on a sieve of 24 mesh size 71 24 to 60 mesh size 24 Passing through a sieve of 60 mesh size 5 Potassium nitrate KNO was used instead of potassium chloride in the formula of Table 6 and the mixture was granulated in the same way as in Example 1. The granu latory distribution was as follows:

Percent Remaining on a sieve of 24 mesh size 68 24 to 60 mesh size 26 Passing through a sieve of 60 mesh size 6 EXAMPLE 9 Sugar (first white) was used instead of potassium chloride in the formula listed in Table 6 and the mixture was granulated in the same way as in Example 1. The granulatory distribution of the composition was as follows:

Percent Remaining on a sieve of 24 mesh size 61 24 to 60 mesh size 33 Passing through a sieve of 60 mesh size 7 We claim:

1. A method for making a granular bleaching product, comprising:

forming a substantially uniform, solid, powdery, dry bleaching composition consisting essentially of from about 10 to about percent by weight of sodium perborate and from about 1 to about 20 percent by weight of at least one granulating assistant selected from the group consisting of magnesium sulfate, beryllium sulfate, potassium chloride, potassium nitrate, sugar and sodium borate, placing said dry bleaching composition in a rotatable container and rotating said container at a speed of from about 15 r.p.m. to about 30 rpm. for a period of at least about two minutes and simultaneously heating said composition to a temperature in the range of from about 64 C. to about C., and then removing said composition from said container whereby to obtain a solid, granular, homogenous, non-agglomerating bleaching product.

2. A method according to claim 1, in which said container is rotated for a period of from about 5 minutes to about 30 minutes.

3. A method according to claim 1, in which the balance of said bleaching agent composition comprises at least one of the following ingredients:

sodium tripolyphosphate;

sodium pyrophosphate;

sodium sulfate;

a surface active agent selected from the group consisting of sodium alkyl benzene sulfonate and sodium higher al'kyl sulfate;

sodium silicate; and

carboxymethyl cellulose.

References Cited UNITED STATES PATENTS 2,876,200 3/ 1959 Strain et a1. 25297 2,979,464 4/1961 Pistor 25299 3,256,198 6/1966 Matzner 25299 3,366,570 1/1968 Slob 25299 MAYER WEINBLATT, Primary Examiner US. Cl. X.R. 252186 

